Clonal mature B-lymphocytes and plasma cells make monoclonal antibodies that can be detected by serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE). These methods are used to diagnose myeloma and other monoclonal gammapathies, and to monitor treatment and disease progression. They are surrogate markers that allowed us to reduce the number of bone marrow biopsies and imaging scans that a patient would have to be subjected to. The detection is more complicated in 10–20% of myeloma patients with light chain myeloma and was impossible in 2–3% patients with „non-secretory“ myeloma. New method is a detection of free light chain (FLC) in serum. In our study we compare those three methods (SPE, IFE and FLC) from the viewpoint of sensitivity of paraprotein detection. For FLC detection was used Freelite system analyzer (Immunotech Beckman Coulter). We examined 51 patients with diagnosis of multiple myeloma, non-Hodgkin lymphoma, primary amyloidosis and monoclonal gammopathy of undetermined significance. Detection of FLC is a valuable method which could sometimes specify diagnosis of MG and make treatment more accurate.

        Key words: multiple myeloma, detection of paraprotein, free light chains (FLC).